The cured silicone particles are used as an additive for cosmetic materials, paints, inks, thermosetting organic resins, thermoplastic organic resins, and the like, and in particular, are preferably used as an internal stress emollient for thermosetting organic resins or as a surface lubricant for organic resin films.
The cured silicone particles are made by curing an addition reaction curable silicone composition or a condensation reaction curable silicone composition, and the particle size differs according to the manufacturing method. Generally, there are limitations to refinement when pulverizing cured material into granular material, and even from an energy cost point of view, a manufacturing method that causes a curing reaction of particulates of the curable silicone composition to provide cured silicone particles with a small particle size is preferable.
However, even if a primary particle is fine, the fine cured particles can easily aggregate to secondary particles, and an aggregate may not easily redisperse to primary particles. This is caused by a phenomenon in which primary particles bond with one another as aggregates, and the bond is difficult to break (dissociate).
There is a problem in which, when cured silicone particles are added to a solvent or the like, the cured silicone particles become secondary aggregates or conglomerates thereof without dispersing at the primary particle size, dispersion is insufficient, and a uniform mixture cannot be prepared, and a composition containing the cured silicone particles cannot sufficiently demonstrate properties of the cured silicone particles. Generally, particles with low hardness such as silicone rubber particulates easily aggregate. Japanese Unexamined Patent Application Publication No. H04-348143 and Japanese Unexamined Patent Application Publication No. H04-353576 respectively propose improving fluidity and dispersibility by attaching inorganic particles to the particle surface of cured silicone particles as a countermeasure. However, there was a problem in which an inorganic feeling of the inorganic particles was transferred to the cured silicone particles.
Japanese Unexamined Patent Application Publication No. H07-197815, Japanese Unexamined Patent Application Publication No. H08-085753, and Japanese Unexamined Patent Application Publication No. H09-020631 respectively propose providing dispersibility and fluidity similar to that of silsesquioxane particulates by attaching silsesquioxane fine particles with high hardness to the particle surface of cured silicone particles. However, there is problem in which the oil absorbing properties of the cured silicone particles are greatly reduced.
Therefore, there is demand for cured silicone particles with weak cohesive properties but high dispersibility, without having to mix a third component such as inorganic fine particles, silsesquioxane particles, or the like.